Webster's New World Medical Dictionary

vomiting of pregnancy, pernicious
See 
hyper-
emesis gravidarum.
vomitus
See 
vomit.
von Hippel-Lindau syndrome
A genetic dis-
ease that is characterized by hemangioblastomas
(benign blood vessel tumors) in the brain, spinal
cord, and retina; kidney cysts, and kidney cancer
(renal cell carcinoma); pheochromocytomas
(benign tumors of adrenal-like tissue); and
endolymphatic sac tumors (benign tumors of the
labyrinth in the inner ear). Abbreviated VHL syn-
drome. The brain hemangioblastomas in VHL syn-
drome are usually in the cerebellum and can cause
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von Hippel-Lindau syndrome
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headache, vomiting, and gait disturbances or
ataxia (wobbliness). The hemangioblastomas in
the retina can cause vision loss and may be the ini-
tial sign of VHL syndrome. The endolymphatic sac
tumors can diminish hearing, which is a key symp-
tom of VHL syndrome. VHL syndrome is inherited
in an autosomal dominant manner and is caused by
a change that affects the VHL gene, a tumor-sup-
pressor gene, on chromosome 3. Molecular
genetic testing for the VHL gene confirms the 
diagnosis of VHL syndrome. Prenatal testing is
available. Early recognition of VHL syndrome is
important because it permits timely intervention
and may be lifesaving. Treatment can involve 
neurosurgery.
von Recklinghausen disease
See 
neurofibro-
matosis.
von Willebrand disease
The most common
inherited bleeding disorder, in which a clotting pro-
tein called von Willebrand factor is deficient or
defective. Von Willebrand factor is made by cells lin-
ing the wall of blood vessels. Several types of von
Willebrand disease have been described. All types
affect both males and females. Symptoms can
include easy bruising, nosebleeds, bleeding from
the gums after a dental procedure, heavy menstrual
bleeding in women, blood in the stool and urine,
and excessive bleeding after a cut or other accident
or after surgery. Von Willebrand disease is usually
mild and often does not require treatment.
Treatment may be needed only after surgery, a tooth
extraction, or an accident. For those who need treat-
ment, medications such as desamino-8-arginine
vasopressin (DDAVP) can be given to raise the lev-
els of von Willebrand factor, which reduces the ten-
dency toward bleeding. Antihemophilic factor
(Alphanate) may be given to decrease bleeding in
patients with the disease who must have surgery or
other invasive procedures. Blood plasma or certain
factor VIII preparations may also be used to
decrease bleeding.